We propose to develop a shape memory polymer (SMP) foam embolic device for treating cerebrovascular aneurysms. The SMP implants are superior to current clinical alternatives in that they 1) acutely clot faster and more completely throughout the aneurysm volume and 2) chronically heal by forming collagenous scars. Cerebral aneurysm rupture occurs in approximately 30,000 people per year in the United States with devastating consequences. Three-fourths of patients will either die or become neurologically debilitated. Given the increasing utilization of CT and MRI scanning, many unruptured aneurysms are being identified as incidental findings, and are commonly treated in order to prevent aneurysm rupture, which carries a >50% risk of severe neurologic dysfunction or death. Current endovascular treatment involves delivery of coils through the arterial system to fill the aneurysm, requiring on average 5- 8 coils to treat a single aneurysm. In 30% of treated aneurysms, the coils migrate or become compressed. This compaction opens a pathway for the blood to re-enter the aneurysm, causing the aneurysm to balloon once more. Coils, since they are metal springs, also present a risk of rupturing the aneurysm they are intended to fill. The healing response to coils is another major deficiency: Chronically the central core region of the aneurysm is composed of loose, cellular connective tissue, foci of debris, and clotted blood, rather than having a more stable fibrocellular composition. In order to apply to the FDA by the end of this study with an IDE application, the following three specific aims are proposed. Specific Aim 1: Engineering, Quality System (QS) and Manufacturing. Specific Aim 2: Design Verification. Specific Aim 3: Design Validation.